Discovering Computers - Chapter 10: Database Management

Discovering Computers - Chapter 10: Database Management Define the term, databaseDefine the term, database; Identify the qualities Identify the qualities of valuable informationof valuable information; Explain why data is important Explain why data is important to an organizationto an organization.

Trang 1

Chapter 10 Database Management

Trang 2

Discuss the terms character,

field, record, and file

Discuss the terms character,

field, record, and file

Identify file maintenance techniques

Differentiate between a file processing system approach and the database approach

Describe characteristics of relational, object-oriented, and multidimensional databases

Explain how to interact with Web databases

Discuss the responsibilities of database analysts and administrators

Next

Define the term, database

Trang 3

Add, change, and delete

Create database

Sort and retrieve

Create forms and reports

Data and Information

(DBMS)

Database software also called database management system

(DBMS)

Trang 4

How are data and information related?

processing

data stored on disk

Step 1 The member data, including a photograph, is entered and stored on the hard disk.

Step 2 The computer extracts the member data from disk.

Step 3 The receipt is created and printed.

 Data is raw facts

 Information is data that is organized

Trang 5

What is data integrity?

 Degree to which data is

incorrect data

Garbage out Garbage in

Data integrity

is lost

Trang 6

Useful Accessible

Organized

What are the qualities of valuable information?

Timely Verifiable

Accurate

Cost-effective

Trang 7

The Hierarchy of Data

What is a hierarchy?

 Database contains files, file contains records, record

contains fields, field contains characters

Trang 8

What is a field ?

 Combination of one or more

characters

 Smallest unit of data user accesses

 Field size defines the maximum

number of characters a field can contain

 Field name uniquely identifies each

field

 Data type specifies kind of data field

contains

Trang 9

Web address that links to

Object

(also called BLOB for binary large object)—photograph, audio, video,

What are common data types?

Currency

dollar and cent amounts or

numbers containing decimal

AutoNumber

unique number automatically assigned to each new record

Trang 10

What is a record ?

Group of related fields

Key field , or primary key , uniquely identifies each record

Trang 11

What is a data file ?

 Collection of related records stored on disk

key

22 Fifth Avenue P.O Box 45

15 Duluth Street

33099 Clark Street

1029 Wolf Avenue Address

Auburn Clanton Prattville Montgomery Montgomery City

AL Weinberg

Jonah

3928

AL Marcus

4872

AL Valesquez

Adrian

3376

AL Murray

Shannon 2928

AL Vandenberg

Donna 2295

State Last Name

First Name Member ID

Green

Trang 12

Maintaining Data

What is file maintenance ?

Changing records Adding records

Deleting records

 Procedures that keep data current

Trang 13

Maintaining Data

Why do you add records?

 Add new record when you obtain new data

Trang 14

Maintaining Data

Why do you change records?

 Correct inaccurate data

 Update old data

Trang 15

Maintaining Data

Why do you delete records?

 When record no longer is needed

 Some programs remove record immediately,

others flag record

Trang 16

Maintaining Data

What is validation ?

 Process of comparing data with a set of rules

to find out if data is correct

 Reduce data entry errors and enhance data

integrity before program writes data on disk

Trang 17

Consistency Check

tests for logical relationship between two or more fields

Consistency Check

tests for logical relationship between two or more fields

Maintaining Data

What are the types of validity checks?

Range Check

determines whether number is within specified range

Range Check

determines whether number is within specified range

Completeness Check

verifies that a required field contains data

Completeness Check

verifies that a required field contains data

Check Digit

number(s) or character(s) appended to or inserted into a primary key value

to confirm accuracy of primary key value

Check Digit

number(s) or character(s) appended to or inserted into a primary key value

to confirm accuracy of primary key value

Alphabetic/

Numeric Check

ensures correct type of data entered

Alphabetic/

Numeric Check

ensures correct type of data entered

Click to view Web

Trang 18

Isolated data—data stored in separate files

so it is difficult to access

Isolated data—data stored in separate files

so it is difficult to access

File Processing Versus Databases

What is a file processing system ?

Data redundancy—

same fields stored in multiple files

Data redundancy—

same fields stored in multiple files

Each department or area within organization has own set of

files

Each department or area within organization has own set of

files

May have weaknesses

Records in one file may not relate to records in any other file

Trang 19

What is the database approach ?

 Many programs and users can share data in database

 Secures data so only authorized users can access

certain data

Trang 20

What are the strengths of the database approach?

Improved data integrity

Shared data

Easier access

Reduced development

time

Reduced development

time

Trang 21

Trang 22

Database Management Systems

What are popular database management systems (DBMSs)?

Click to view Web

Link, click Chapter 10,

Click Web Link from left

navigation, then click

Database Management System

below Chapter 10

Trang 23

What is a data dictionary ?

 Contains data about each file in database and each

field within those files

Click to view Web

Trang 24

What is a query ?

 Request for specific data from

a database

 Query language consists of

simple, English-like statements

that allow users to specify data

to display, print, or store

Step 1 Select the fields you want

to display in the resulting query.

Step 2 Assign a name to the query, so you can open it later.

Step 3 View query on the screen.

Trang 25

What is a query by example (QBE) ?

 Program retrieves records that match criteria

entered in form fields

Query by example screen

criteria Query results

 Has a graphical user interface that assists users

with retrieving data

Trang 26

What is a form ?

 Window on screen that provides areas for entering or

changing data in database

 Used to retrieve and

maintain data in a

database

 Form that sends

data across network

or Internet is called

e-form, short for

electronic form

Trang 27

What is a report generator ?

 Allows user to design a report on screen, retrieve

data into report design, then display or print

reports

 Also called

report writer

Trang 28

What is data security?

Read-only privileges - user can view data, but cannot change it

DBMS provides means to ensure only authorized users can access

data

DBMS provides means to ensure only authorized users can access

data

Access privileges

define activities that specific user

or group of users can perform

Access privileges

define activities that specific user

or group of users can perform

Full-update privileges - user can view and change data

Trang 29

What are backup and log ?

 Backup is a copy of the

entire database

 Log is a listing of activities

that change database

contents

 DBMS places three items

in log: before image, actual change, and after image

before image

change after image

Trang 30

What is a recovery utility ?

Also called forward recovery

Rollback —DBMS uses log to undo any changes made to database during a certain period of time

Also called backward recovery

Click to view Web

Link, click Chapter 10, Click

Web Link from left

Backup and Recovery below

Chapter 10

Trang 31

Relational, Object-Oriented, and Multidimensional Databases

What is a data model ?

 Rules and standards that

define how database

Trang 32

What is a relational database ?

 Stores data in tables that consist of rows and columns

 Stores data relationships

 Uses specialized terminology

Click to view Web

Web Link from left

Relational Databases below

Chapter 10

Trang 33

What is a relationship ?

 Connection

within data

Trang 34

What is Structured Query Language (SQL) ?

 Allows you to manage, update, and retrieve data

 Has special keywords and rules included in SQL

statements

SQL statement

SQL statement results

Click to view Web

Web Link from left

SQL below Chapter 10

Trang 35

What is an object-oriented database (OODB) ?

Advantages

Often uses object query language (OQL)

Stores data in objects Object

is item that contains data,

as well as actions that read or process data

 Can store more types of data

 Can access data faster

Click to view Web

Trang 36

What are examples of applications appropriate for an

object-oriented database?

Multimedia databases

Store images, audio clips,

and/or video clips

Store images, audio clips,

and/or video clips

Groupware databases

Store documents such as schedules, calendars, manuals,

memos, and reports

Store documents such as schedules, calendars, manuals,

memos, and reports

and scientific designs

Store data about engineering, architectural,

and scientific designs

Contain text, graphics,

video, and sound

Contain text, graphics,

video, and sound

Web databases

Link to e-form on Web page

Trang 37

What is a multidimensional database ?

Stores data in dimensions

Multiple dimensions, also called hypercube , allow users

to analyze any view of data

Can consolidate data much faster than relational database

Click to view Web

Trang 38

What is a data warehouse ?

Data mart is smaller version of data warehouse

Uses multidimensional databases

Often uses a process called

data mining to find patterns and relationships among data

Huge database system that stores and manages data required to analyze historical and current transactions

Quick and efficient way to access large amounts of data

Click to view Web

Web Link from left

Data Warehouses below

Chapter 10

Trang 39

Web Databases

What is a Web database?

 Database you access through the Web by filling in a form

Trang 40

3 Design the records and fields for each table

2 Design the tables

1 Determine the purpose of the database

 Design tables on paper first

 Each table should contain

data about one subject

 Allow enough space for each field

 Set default values for frequently entered data

Trang 41

 Focuses on meaning and usage of data

 Decides proper placement

of fields, defines relationships, and identifies users’ access privileges

 Creates and maintains data dictionary, manages

database security, monitors database performance, and checks backup and recovery

procedures

Click to view Web

Trang 42

Summary of Database Management

Chapter 10 Complete

How data and information are

valuable assets to an organization

How data and information are

valuable assets to an organization

Methods for maintaining

Advantages of organizing data in a database

Various types of databases

Role of the database analysts and administrators Role of the database analysts and administrators

Định dạng
Số trang	42
Dung lượng	4,22 MB